Quentin Tarantino’s “Once Upon a Time ... in Hollywood” is a rambling, aimless, 161-minute love letter to Los Angeles and 1969, a year that has been in the news a lot lately thanks to that whole moon landing thing. But, this being Tarantino, it’s a love letter scrawled in pop-culture cool and B-movie blood that turns into a film that, like a guitar solo from the era, may be far too long but is wily and inventive nonetheless.

1969 is an intriguing year for a number of reasons. It’s the era when the peace and love of Woodstock (August) curdled into the violence and mayhem of Altamont (December). It’s the era on the cusp between the old Hollywood studio system and the up-and-coming cinematic revolutionaries who would challenge all of that in the ’70s.

Rick Dalton (Leonardo DiCaprio) finds himself surfing the shifting sands of changing times as a once-popular TV cowboy actor in LA who’s struggling to keep his career afloat. Sure, he has work and maintains his lavish Hollywood Hills lifestyle, but he has lost his leading-man status and is now being cast as the disposable villain in episodic TV shows like “The F.B.I.” As producer Marvin Schwarzs (Al Pacino) tells him that can only mean two things: He’s either going to get beat up or die all the time — and that’s not a good look for his image; and his career is on a downward trajectory. Unless, of course, he takes Marvin’s advice and moves to Rome to star in spaghetti Westerns.

Trying to keep Rick’s spirits up is Cliff Booth (Brad Pitt), Rick’s former stunt double, good friend, drinking buddy and driver (in the latter capacity, he gets to tool through town in a beautiful Cadillac land yacht, not a bad way to get around LA). Like Rick, Cliff’s best days may be behind him, too.

As Rick fights to maintain his relevance, his neighbors next door have no such problems. Director Roman Polanski (Rafal Zawierucha) and his wife, Sharon Tate (Margot Robbie), are the celebrated new kids in town, thanks to Polanski’s much talked-about 1968 film “Rosemary’s Baby.” Rick dreams of getting cast in Polanski’s next picture.

All the while, free-spirited, hitchhiking hippies, including one named Pussycat (Margaret Qualley) who catches Cliff’s eye, have become like street furniture across LA, their sometimes threatening presence — Charles Manson (Damon Herriman) makes a brief appearance — hinting at the death of the counterculture dream to come.

How all these worlds ultimately collide provides the film’s loose narrative tension. But Tarantino takes a circuitous route to get there, leading viewers on a drive through late-’60s Los Angeles that is never less than fascinating. No one does fanboy pop-culture shoutouts quite like Tarantino, and he’s in top form here.

“Once Upon a Time ... in Hollywood”

From the wall-to-wall music — Deep Purple’s “Hush,” Otis Redding’s “I Can’t Turn You Loose,” Bob Seger System’s “Rambling Gambling Man,” The Rolling Stones’ “Out of Time” and so much more — to such LA-specific characters as horror-movie TV host Seymour, Tarantino makes you feel as if he really has turned back the clock. (Though, it has to be noted, that it seems unlikely that these characters — the hipsters of their day — would all be listening to mega-Top 40 powerhouse radio station KHJ-AM for hits from Paul Revere & the Raiders, as they do here. They’d probably be tuning in, turning on and dropping out to one of those newfangled, hip, free-form progressive-rock FM stations to hear the likes of The Doors and Frank Zappa, some of whom would also have been their neighbors in the hills and canyons overlooking LA.)

DiCaprio is at his loose-limbed best, and there’s a buddy-movie chemistry between DiCaprio and Pitt that’s palpable and often very humorous, especially when Tarantino pokes behind-the-scenes fun at how the cinematic sausage gets made.

For all of its charms though, “Once Upon a Time … in Hollywood” — while much better than such recent overblown Tarantino projects as “Django Unchained” and “The Hateful Eight” — doesn’t reach the heights of the director's best films, such as “Jackie Brown” and “Pulp Fiction.” It feels like a somewhat minor work, a lark, in the Tarantino universe. It also squanders Margot Robbie, who doesn’t have much to do. The tonal shift, from breezy to something much more visceral and darker by the end, might rankle some not used to the director’s style.

Still, it ranks as one of the highlights of the summer. Besides, now that this long-awaited project is finally out of the way, we can start counting down to Tarantino’s next film: his probable R-rated take on the “Star Trek” universe. The line starts here.

Cary Darling joined the Houston Chronicle in 2017 where he writes about arts, entertainment and pop culture, with an emphasis on film and media. Originally from Los Angeles and a graduate of Loyola Marymount University, he has been a features reporter or editor at the Orange County Register, Miami Herald, and the Fort Worth Star-Telegram. In addition, he has freelanced for a number of publications including the Los Angeles Times and Dallas Morning News.